900 flying hours over 10 months is not so hard. Did it for years in my youth. The only thing better than that would be 900 hours in 9 months and have 3 off. Once I did 1000 with a foreign operator in just under 10 months and had a great time with the enforced leave for the rest of the year. As long as the hours can be flown at civilised hours and not lots of late nights or early mornings back to back. You gotta love your leave and treat it as sacrosanct. I always, always took it, never let them pay me filthy money instead. Hence I am still healthy, touch wood. Lots of American operators get 1000 or more and only allow 2 weeks leave. Now that's hard and potentially life-threatening and shame on the FAA for allowing it.
Any pilot who sells leave back to the Company is letting the side down big time. Management only see this as proof we are driven by greed and destroys the safety argument.
IMHO it it is not the flying hours that makes or breaks the spirit, it is all the duty time and crewing patterns that need to be factored in by the health experts and fatigue management systems.
When fatigue gets dangerous pilots absolutely owe it to themselves to go sick or go elsewhere. One of the few times that I ever flew when seriously fatigued I made an error of judgement that could have been expensive for the operator. While it might have served them right, it would not have looked good on the resume so I resolved to just go sick if I ever got too tired again.